– GMPR, also known as GMPR1, belongs to the IMPDH/GMPR family.This familyofenzymesincludesIMP dehydrogenaseandGMP reductase. These enzymes are involved inpurine metabolism and adopt aTIM barrelstructure. GMPR is an enzyme that catalyzes the irreversible and NADPH-dependent reductive deamination of GMP to IMP. GMPR functions in the conversion of nucleobase, nucleoside and nucleotide derivatives of G to A nucleotides, and in maintaining the intracellular balance of A and G nucleotides.